Fix

Technosoftware/DaAeHdaClient.Com/EnumString.cs

@@ -0,0 +1,128 @@
+#region Copyright (c) 2011-2023 Technosoftware GmbH. All rights reserved
+//-----------------------------------------------------------------------------
+// Copyright (c) 2011-2023 Technosoftware GmbH. All rights reserved
+// Web: https://www.technosoftware.com 
+// 
+// The source code in this file is covered under a dual-license scenario:
+//   - Owner of a purchased license: SCLA 1.0
+//   - GPL V3: everybody else
+//
+// SCLA license terms accompanied with this source code.
+// See SCLA 1.0: https://technosoftware.com/license/Source_Code_License_Agreement.pdf
+//
+// GNU General Public License as published by the Free Software Foundation;
+// version 3 of the License are accompanied with this source code.
+// See https://technosoftware.com/license/GPLv3License.txt
+//
+// This source code is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+// or FITNESS FOR A PARTICULAR PURPOSE.
+//-----------------------------------------------------------------------------
+#endregion Copyright (c) 2011-2023 Technosoftware GmbH. All rights reserved
+
+#region Using Directives
+using System;
+using System.Runtime.InteropServices;
+using Technosoftware.OpcRcw.Comn;
+#endregion
+
+namespace Technosoftware.DaAeHdaClient.Com
+{
+    /// <summary>
+    /// A wrapper for the COM IEnumString interface.
+    /// </summary>
+    internal class EnumString : IDisposable
+    {   
+        /// <summary>
+        /// A reference to the remote COM object.
+        /// </summary>
+        private IEnumString m_enumerator = null;
+
+        /// <summary>
+        /// Initializes the object with an enumerator.
+        /// </summary>
+        public EnumString(object enumerator)
+        {
+            m_enumerator = (IEnumString)enumerator;
+        }
+        
+        /// <summary>
+        /// Releases the remote COM object.
+        /// </summary>
+        public void Dispose()
+        {
+            Utilities.Interop.ReleaseServer(m_enumerator);
+            m_enumerator = null;
+        }
+
+        //=====================================================================
+        // IEnumString
+
+        /// <summary>
+        /// Fetches the next subscription of strings. 
+        /// </summary>
+        public string[] Next(int count)
+        {
+            try
+            {
+                // create buffer.
+                var buffer = Marshal.AllocCoTaskMem(Marshal.SizeOf(typeof(IntPtr))*count);
+
+                try
+                {
+                    // fetch next subscription of strings.
+                    var fetched = 0;
+
+                    m_enumerator.RemoteNext(
+                        count,
+                        buffer,
+                        out fetched);
+
+                    // return empty array if at end of list.
+                    if (fetched == 0)
+                    {
+                        return new string[0];
+                    }
+
+                    return Interop.GetUnicodeStrings(ref buffer, fetched, true);
+                }
+                finally
+                {
+                    Marshal.FreeCoTaskMem(buffer);
+                }
+            }
+
+            // return null on any error.
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// Skips a number of strings.
+        /// </summary>
+        public void Skip(int count)
+        {
+            m_enumerator.Skip(count);
+        }
+
+        /// <summary>
+        /// Sets pointer to the start of the list.
+        /// </summary>
+        public void Reset()
+        {
+            m_enumerator.Reset();
+        }
+
+        /// <summary>
+        /// Clones the enumerator.
+        /// </summary>
+        public EnumString Clone()
+        {
+            IEnumString enumerator;
+            m_enumerator.Clone(out enumerator);
+            return new EnumString(enumerator);
+        }
+    }
+}